(1). Field of the Invention
This invention relates to a fuse assembly and more specifically, to a fuse assembly that can securely halt an electric power supply to a load after a blowout of a fuse element in the fuse assembly.
(2). Description of the Related Art
In a vehicle as a mobile unit, many electric power transfer lines for transferring electric power itself or signals, such as busbars in an electric junction box such as a junction block, relay box and fuse block, and terminals of a connector for electric connection, are disposed.
In the electric power transfer lines, a fuse block, in which many fuses that can be inserted or extracted are disposed, is employed to protect electric circuits of various electrical equipments. (The fuse block may be called a relay box, junction block or electric junction box as the general term since the fuse block may have relays or busbars. In this specification, the aforementioned fuse block, relay box and junction block are hereinafter called an electric junction box as the general term.)
For example, a fuse assembly 101 shown in FIG. 5 has been employed as a fuse for use in the electric junction box. As shown in FIGS. 5 and 6, the fuse assembly 101 includes a pair of terminals 102 arranged in parallel with each other, a housing 104 for receiving ends 103 of the terminals 102, and a fuse element 105 formed integrally with a pair of the terminals 102 for connecting the terminals 102 with each other.
The terminal 102 is made of an electrically conductive metal and is formed in a blade-shape as shown in FIG. 6. The terminal 102 is provided with a plurality of through holes 106. Each terminal 102 shown in FIGS. 5 and 6 has two through holes 106. The through holes 106 are disposed in parallel with each other along the direction of the length of the terminal 102. One through hole 106 is formed at the center 107 of the terminal 102 along the direction of the length of the terminal 102 and another through hole 102 is formed around the end 103 of the terminal 102.
When the fuse assembly 101 is mounted in the electric junction box, each opposite end 108 of a pair of the terminals 102 is connected to respective receiving terminals of the electric junction box. An electric power is supplied to one of the receiving terminals from an electric power source or the like, while various loads are electrically connected to an opposite receiving terminal.
An electric power is supplied to one of the terminals 102 through the receiving terminal and the like, while the load is connected to another terminal 102. Each end 103 of the terminals 102 is received into the housing 104 with each inner surface 109 of the terminals 102 facing with each other.
The housing 104 is made of insulating synthetic resin and the like. The housing 104 is formed in a box-shape. The inside of the housing 104 is a receiving space for receiving each end 103 of a pair of the terminals 102. The housing 104 is provided with each projection (not shown in the figure) for engaging with the respective through holes 106. When each projection is engaged with the respective through hole 106, a pair of the terminals 102 is fixed in the housing 104.
As shown in FIG. 6, the fuse element 105 connects the terminals 102 with each other. Each end of the fuse element 105 is connected to the inner surface 109 situated at the center 107 of the terminal 102. The thickness of the fuse element 105 is about uniformly formed between one connection part 105a connecting with one terminal 102 and another connection part 105b connecting with another terminal 102. The fuse element 105 blows out when a current of an electric power supplied from one of the terminals 102 exceeds a predetermined current value.
As to the fuse assembly 101 mounted in the electric junction box, when a current value of an electric power supplied to the one terminal 102 through the one receiving terminal or the like exceeds a predetermined current value, the fuse element 105 blows out so as to halt the power supply to the load.
As to a conventional fuse 101 shown in FIG. 5, the thickness of the fuse element 105 is about uniformly formed between one connection part 105a connecting with one terminal 102 and another connection part 105b connecting with another terminal 102. The fuse element 105 tends to blow out at the thinnest portion thereof. The thinnest portion may be located at any portion of the fuse element 105 between one connection part 105a and another connection part 105b, due to a variation in the manufacturing process. That is, the thinnest portion of the fuse element 105 may be different among the fuse assemblies 101.
Therefore, as to the conventional fuse assembly 101, the fuse element 105 may blow out at any portion of the fuse element 105 between one connection part 105a and another connection part 105b. For example, when the fuse element 105 blows out in the vicinity of one connection part out of the connection part 105a and the connection part 105b, the fuse element 105 connected to an opposite connection part becomes in a so-called cantilever state.
At this time, due to a vibration of the vehicle during the traveling or a sudden acceleration, the fuse element 105 vibrates in the housing 104 and then, a pair of the blown-out portions of the fuse element 105 may come into contact with each other, resulting in that the blown-out fuse element 105 may electrically connect a pair of the terminals 102 with each other.
It is therefore an objective of the present invention to solve the above problem and to provide a fuse assembly which can securely halt an electric power supply to a load after a blowout of a fuse element in the fuse assembly.
In order to attain the above objective, the present invention is to provide a fuse assembly comprising: a pair of terminals arranged in parallel with each other; a housing for receiving each one end of a pair of the terminals; and a fuse element for connecting a pair of the terminals with each other, wherein a thickness of the fuse element at the central part thereof situated at the center between a pair of the terminals is smaller than the thickness of the fuse element at each connection part with the terminal.
According to the fuse assembly described above, since a thickness of the fuse element at the central part thereof situated at the center between a pair of the terminals is formed smaller than a thickness of the fuse element at each connection part with the terminal, therefore the central part of the fuse element blows out.
The thickness of the fuse element continuously or gradually decreases from said each connection part to said central part of the fuse element.
According to the fuse assembly described above, the central part of the fuse element securely blows out.
The fuse element comprises: a pair of supporting parts which contains said connection parts and is connected to each end surface situated at an end of a pair of the terminals, said central part connecting a pair of the supporting parts with each other; and a fixing part for fixing each supporting part of the fuse element to the housing.
According to the fuse assembly described above, since the fixing part fixes each supporting part of the fuse element to the housing, therefore the fuse element hardly vibrates in relation to the terminals.